Summary of RFMD IQ modulator has fractional-N synthesiser
The RFMD2080 is a low-power, highly integrated IQ modulator with a fractional-N synthesizer and VCO, covering RF outputs from 45 MHz to 2700 MHz. It offers ultra-fine frequency step size (~1.5 Hz), low spurious levels, integrated wideband VCOs/LO buffers, programmable baseband gain and filtering (1.5–10 MHz bandwidth), DC offset control for carrier suppression, and a serial programming interface. Typical specs: <0.2° rms phase noise at 1 GHz, -150 dBm/Hz noise floor, +4 dBm P1dB, +18 dBm IP3, 3.0–3.3 V supply, ~155 mA current. Packaged in a 5x5 mm QFN.
Parts used in the RFMD2080 Project:
- RFMD2080 IQ modulator IC
- External loop filter (for synthesizer/VCO)
- External VCO or LO source (optional differential input)
- Supply voltage 3.0V to 3.3V
- 3-wire serial programming interface connections
- QFN 5x5 mm package (device package)
- Baseband I and Q input circuitry (variable gain and filtering)
- Quadrature divider (/2) internal to device (buffered LO divider)
- RF matching and output network to support 45MHz–2700MHz
- PCB and connectors for satellite/point-to-point/software defined radio applications
Product Description
The RFMD2080 is a low power, highly integrated, IQ modulator with integrated fractional-N synthesizer and voltage controlled oscillator (VCO). The RFMD2080 can generate output frequencies of between 45MHz and 2700MHz, making it suitable for a wide range of applications.
The fractional-N synthesizer takes advantage of an advanced sigma-delta architecture that delivers ultra-fine step sizes and low spurious products. The synthesizer/VCO combined with an external loop filter allows the user to generate an oscillator signal covering 90MHz to 5400MHz. The signal is buffered and routed to a high accuracy quadrature divider (/2) that drives the balanced I and Q mixers. The output of the mixers are summed and applied to a differential RF output stage. The device also features a differential input for an external VCO or LO source.
The baseband I and Q stages are highly integrated; featuring variable gain and filtering as well as generation of DC offset voltages. The programmable DC offsets enable improved carrier suppression. The baseband input 3dB bandwidth can be tuned from 1.5MHz to 10MHz, and the total gain control range is 38dB with 2dB resolution.
Features
- RF Output Frequency Range 45MHz to 2700MHz
- Fractional-N Synthesizer with Very Low Spurious Levels
- Typical Step Size 1.5Hz
- Fully Integrated Wideband VCOs and LO Buffers
- Integrated Phase Noise <0.2° rms at 1GHz
- Integrated Baseband Amplification Stage with Variable Gain and Filtering
- Tunable Baseband Filters Input 3dB Bandwidth from 1.5MHz to 10MHz
- -45dBc Unadjusted Carrier Suppression
- -40dBc Unadjusted Sideband Suppression
- Very Low Noise Floor -150dBm/Hz Typical
- Output P1dB +4dBm
- Output IP3 +18dBm
- 3.0V to 3.3V Power Supply
- 155mA Typical Current Consumption
- Serial Programming Interface
RF Micro Devices has introduced two low power IQ modulators featuring integrated fractional-N synthesisers and voltage controlled oscillators (VCO).
The RFMD2080 and RFMD2081 devices are capable of generating output frequencies from 45MHz to 2700MHz.
They are suitable for a wide range of applications, including satellite communications, point-to-point radio, software defined radio, and other wireless and wireline applications requiring QPSK/QAM modulators.
The RFMD2080 features a baseband interface incorporating programmable filtering and gain control.
Optimised for low power operation, the device has current consumption of 150mA from a 3V supply.
Both the RFMD2080 and RFMD2081 are programmable using a simple 3-wire serial interface and offered in QFN 5x5mm packages.
RFMD will exhibit the above components at the IEEE International Microwave Symposium (IMS) 2011, June 6-8, at the Baltimore Convention Center, in Booth 1402.
For more read: RFMD IQ modulator has fractional-N synthesiser
- What RF output frequency range does the RFMD2080 support?
The RFMD2080 supports RF output frequencies from 45MHz to 2700MHz. - Can the RFMD2080 generate fine frequency steps?
Yes, it uses a fractional-N synthesizer with a typical step size of 1.5Hz. - Does the RFMD2080 include an integrated VCO?
Yes, it has fully integrated wideband VCOs and LO buffers. - What baseband input bandwidths are available?
The tunable baseband input 3dB bandwidth ranges from 1.5MHz to 10MHz. - How is the device programmed?
It is programmable using a simple 3-wire serial interface. - What are typical power and current requirements?
The device operates from a 3.0V to 3.3V supply with typical current consumption around 155mA. - What carrier and sideband suppression performance is typical?
Typical unadjusted carrier suppression is -45dBc and sideband suppression is -40dBc. - What are the RF output linearity specifications?
Typical output P1dB is +4dBm and output IP3 is +18dBm. - Is there support for an external LO or VCO?
Yes, the device features a differential input for an external VCO or LO source. - What package is the RFMD2080 offered in?
It is offered in a QFN 5x5 mm package.
